Split notochord syndrome: a case in point

A 36-year-old female presented with low back pain and was admitted. During the anamnesis, she reported having undergone surgery, in the first days of life, for the repair of lumbosacral myelomeningocele and imperforate anus. She had been a full-term infant, born to an adolescent mother who had received no prenatal care. There were no reports of infection, drug use, or exposure to teratogenic agents during gestation. Computed tomography of the urinary tract showed ectopic kidneys, with a rotational anomaly and bilateral nephrolithiasis. In addition, as an incidental finding, we identified a congenital (morphological and structural) alteration of the lumbosacral spine, characterized by a fusion defect and failure of vertebral body segmentation, with the formation of two axes, starting from the third lumbar vertebra. Other imaging tests for the evaluation of the lumbosacral spine confirmed the findings and demonstrated two medullas within a single dural sac, separated by a thin fibrous septum (Figure 1). These findings, taken together with the clinical history, suggested split notochord syndrome (SNS) as the most likely diagnosis. SNS results from a rare congenital malformation defined as a cleft in the spine, forming a double spinal column, due to failed fusion of the lateral ossification centers of the vertebral bodies. It occurs most often in the thoracolumbar region; when it affects the lumbosacral region, it can be accompanied by imperforate anus and meningocele. Other anomalies, involving the gastrointestinal tract, central nervous system, and genitourinary tract—manifesting as dorsal enteric fistulas, hydrocephalus, and bladder exstrophy—have been reported. Given the scarcity of published cases, it is not possible to accurately establish associations with other abnormalities. An extensive review of the literature showed that approximately 500 cases have been reported and that only a minority of the affected individuals reach adulthood. In most cases of SNS, there are no reports of known exposure to teratogenic agents or a family history of birth defects.